1. Field of the Invention
The present invention relates to an electronic control device, used in an automobile, a robot and the like, having a battery as a power source, a built-in boost circuit, and built-in lead-insertion-type parts such as coils and capacitors.
With regard to automobiles, advanced electronic control is used from demand for mileage, tightening regulations for exhaust gas, safety, amenity, and quietness. For such advanced electronic control, an automobile uses a variety of electronic parts, and the high performance and high output power of these electronic parts increase the amount of heat release. Accordingly, cooling technology becomes important for those electronic parts.
There are disclosed the following cooling technologies for such electronic parts.
An engine controller cooling technology by interposing a heat radiation seat between a substrate on which electronic parts are mounted and a lid is known as indicated in Japanese Patent Application Publication No. 2004-119533.
As shown in Japanese Patent Application Publication No. 2005-245149, a power converter is known in which: a high-heat-conductive sheet is disposed between a capacitor and a base; and a high temperature conduction member is installed on the back side of a capacitor-mounting side of the base.
As illustrated in Japanese Patent Application Publication No. 2004-350400, a power converter is known in which: a high-heat-conductive sheet is disposed between a lid portion that thermally comes in contact with a smoothing capacitor and a base; and a high temperature conduction member is installed on the back side of a capacitor-mounting side of the base.
2. Description of the Related Art
Nowadays, actuators are frequently used for automobiles, and electronic control devices tend to be made highly powerful. On the other hand, from the viewpoints of environmental problems, attention is paid to direct injection gasoline engines that are capable of reducing the amount of exhaust nitrogen oxide and of achieving fuel saving. This engine is designed to inject a combustible high density fuel only into the vicinity of a sparking plug, and to burn the fuel super-sparsely as a whole in the cylinder. An injector is used for this fuel injection. This injector must have a high output power since it needs to use a fuel pressurized in a high pressure. Generation of a high output power needs a large electric power that is determined by the product of current multiplied by voltage. An electric current for automobiles is supplied from a battery of about 12 V, which is a low voltage, and thus generation of a high output power with an increase of the current has limitation. This is because an increase of the current remarkably increases the amount of heat release by wire resistance since the amount of heat release is proportional to the second power of the current amount. Hence, there is a need for the generation of a voltage of 50 V or higher by means of a boost circuit.
Here, although the engine control unit for a direct injection gasoline engine has been illustrated as the example, an electronic control device using a battery as a power source, as in the case of the direct injection gasoline engine, has been increasingly requiring a boost circuit to be added to existing functions in order to achieve a high output power.
This boost circuit needs a coil and a capacitor that can endure voltage and current after boost. An electrolyte needs to be thickened to increase the pressure resistance of the capacitor, whereby the size of the capacitor will be enlarged even for the same capacity. For the coil, a troidal coil that uses ferrite or dust core is frequently used because a large amount of current is passed through the coil.
Such a coil and a capacitor are electronic lead-insertion-type parts, having a problem that automatic mounting of the lead-insertion-type parts on a circuit board requires considerable time and efforts, and also increases the frequency of error occurrence. In particular, a troidal coil is low in size precision, and shows a dimensional tolerance of about ±1 mm.
Because of this, the addition of a boost circuit to a conventionally used electronic control device poses problems that: a capacitor and a coil need to be attached outside; a great structural change is needed; and productivity is remarkably worsened. In addition, such a coil and a capacitor generate heat or are low in heat resistance, so that they need to be cooled. Hence, the coil and the capacitor have a problem that the cooling structure becomes complex when they are dispersedly mounted on a circuit board.
Because a heat radiation seat is interposed between a printed wiring board and a lid in Japanese Patent Application Publication No. 2004-119533, it is difficult to apply this technology to lead-insertion-type parts. Moreover, Japanese Patent Application Publications Nos. 2005-245149 and 2004-350400 do not relate to the lead-insertion-type parts, but relate only to the cooling technology for capacitors that are large-scale and fixed by screw clamps or the like. Additionally, since the above patent documents are based on the object to cool capacitor parts of the same, their application to various parts with different shapes and sizes is difficult.
The present invention has been made in consideration of the above problems and aims to provide a small, low-cost electronic control device that includes built-in lead-insertion-type parts such as a coil and a capacitor used for a boost circuit or the like, and its manufacturing method.